5/22/2018Texas Experiment: Longer Yellow Times Reduced Violations
Denton, Texas tested the effect of an extra second of yellow time, and red light camera violations instantly dropped 62 percent.
The city council in Denton, Texas, later today will debate whether to renew a contract with embattled Redflex Traffic Systems of Australia after a test demonstrated an effective alternative to red light cameras. At the urging of council members, city staff tested the effect of an extra second of yellow warning time for the traffic signal at the corner of West Oak Street and North Carroll Boulevard. The experiment took place in April, and it took no time for the results to become obvious -- a 62 percent reduction in red light violations.
"The observed reduction in violation immediately after the implementation of the increased yellow change interval was an expected outcome," police chief Lee Howell wrote in a memo to city manager Todd Hileman.
In the past five years, April violations at the location averaged 74.5 without dropping significantly until the timing change was implemented. Violations fell to just 28. This was not good news to the police chief, who argued strenuously against lengthening the yellow time.
"Drivers that would have run the red light are now doing so during the yellow change interval," Chief Howell wrote. "It should be noted that the pilot program was only implemented for a period of one month, which is not enough to change driver behavior. If this increased yellow change interval is implemented for a longer period of time, drivers will start noticing it and will adjust their behavior accordingly."
With 33,712 photo tickets generated in Denton last year, a 62 percent cut in the violation rate would reduce the program's potential annual profit by $1,567,608. That, in turn, would cut into the pocketbooks of several members of the police force. As investigative reporters at the Denton Record Chronicle newspaper discovered, assistant police chief Scott Fletcher personally took home $135,587 from overtime he claimed while "reviewing" red light camera tickets -- money earned on top of his regular salary. The red light camera program also added $62,555 to the pay of police Lieutenant David Hildebrand and $44,751 to the salary of Sergeant Daryn Briggs.
Noting the reluctance of municipal officials to extend yellow light times, the states of Georgia and Ohio mandated an extra second of yellow wherever red light cameras are used. As TheNewspaper documented, Georgia's red light violations immediately plunged between 70 and 80 percent, and in Ohio violations likewise plummeted as drivers had more time to get through intersections safely. A study by the Texas Transportation Institute explained that the majority of straight-through red light violations happen when a driver misjudges the end of the yellow light by less than 0.25 seconds (view chart). The TTI study found longer yellows also reduced accidents (view report).